I've searched but somehow could not find any threads specifically covering my issue.

I recently purchased a CPO 2008 335 as listed on my profile. Absolutely love the car, but I'm receiving numerous complaints from my parents and girlfriend about the quality of the sound while I'm speaking with them over bluetooth.

For reference, I use a Galaxy S3 so I don't think the phone itself is an issue--calls were crystal clear on others' end when in my old car using an aftermarket navi, and I've also been told that the bluetooth in the loaner car I was given sounds almost as clear as that. The loaner car was a 2011 328 with idrive, for reference. I also have iDrive in my car.

Any ideas? Is this an issue, possibly with the mic that can be covered by CPO?